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Led lighting (merged)

Which AeroLed do you have?

United Kingdom

The standard non-pulse type, 28V. Sunspot 36.

Oddly enough my old lamps have been there for about 10 years / 1300hrs airborne time, without a failure.

I have done some more tests. Both the landing and taxi lamps drop from 1.6A to 0.6A, with a corresponding decrease in brightness. Oddly enough the brightness drop commences immediately after turn-on i.e. they do not implement some sort of temperature limit and dim when the lamp is above that. So I don't know how they can quote a brightness figure at all.

Interestingly their email address [email protected] returns "undeliverable"

They took weeks and weeks to turn up, too, at my US contact.

I will do some tests side by side with a normal GE lamp, because I don't want one of these to be less bright after flying with it for a few minutes.

Administrator
Shoreham EGKA, United Kingdom

Any difference in behavior if you point a strong blower at it or put it in a fridge?

PS: More than once I got comments from the tower like "could you turn off those damn landing lights of yours, I'm blinded". I keep them on at all times on the ground and in the air. My next upgrade will be LED nav lights with a blinking circuit.

The blinking lights must help visibility massively, but they would be a red rag to a bull to any German CAA inspector because I am damn sure they cannot be simply fitted to a Euro reg CofA plane.

Administrator
Shoreham EGKA, United Kingdom

They can because they just replace the light bulbs and at least for Cessnas, the lights are household items. You make them blink by turning them on, off and on again within 3 seconds.

Even if anybody objected, the worst consequence would be that I'd have to put in the old bulbs again. In the 60s blinking nav lights were common.

I'd fancy the 5k lumen version 46LX and a 36LX for taxi. My lights are on the main landing gear and last not very long. There is lots of movement right after turning off the lights and the hydraulics ramming the gear in does not help with long bulb life.

United Kingdom

I too would have gone for the 46 but the Socata wing metalwork makes that impossible.

I have to say I found Aeroleds a very strange company. They NEVER replied to any emails or faxes about how I can buy their products, their main email address is defunct (and they don't seem to care) and the LEDs I ordered (via a US contact - due to their total lack of any communication) tooks a very long time to turn up.

I have just emailed them asking how they measure their claimed brightness, when in fact the brightness starts to go down the instant you apply power and is way lower a few minutes later. If they reply I will post it here.

Administrator
Shoreham EGKA, United Kingdom

A graph of how the current drops off over time - here

At the end, the temperature of the back of the lamp is +74C.

The ambient was +20C.

The response from Aeroleds is:

Your data shows what I would expect with no airflow, after about 6 to 7 minutes it heats up enough for the thermal protection to kick in. The slight drop prior to that is simply due to the Schottky diodes forward voltage dropping as they warm up, reducing the power loss (which provide a slight drop in current). I'm sure you are aware of the change in diode voltage drop as they heat up...

That sounds plausible. At least they are responding now...

The extent to which this is going to matter depends on the ventilation in wherever the lamp is mounted. It takes a lot of forced air to make a difference; I tried it with a hair dryer set to COLD and one had to hold it right on the back of the lamp to bring it back to over 1.2A.

I don't think there is any significant airflow inside the Socata TB wing. The lamp unit is at the end of the wing and the end of the wing is plugged by the tightly fitting wingtip. Also, ACF50 sprayed in there looks still wet after a year.

I think using some heat conductive (aluminium oxide) grease would be a good idea.

Also a 50% drop in light output is not likely to be too visible to the human eye.

Just be careful to not compare these LED lamps on their specification They can look a lot better if the light output is measured in the first few seconds.

Administrator
Shoreham EGKA, United Kingdom

...using some heat conductive (aluminium oxide) grease would be a good idea.

That should solve it - assuming good thermal conduction from the LED to the areas of contact with the wing, an aluminium wing should be a pretty good heat-sink, even without much airflow...

A Copper wing would be twice as good, but probably too heavy (on the other hand, a bare copper wing would look seriously good!)

On a more sober note, one of the LED lights fitted to an aircraft I am using occasionally failed after less than 6 months in service. Will try to find out more...

Biggin Hill

Do the Aeroleds have a massive heat sink like the Alphabeams? I am lucky that in my Cessna, the lamps are under the cowling right in the airflow. Also there is a good contact with the cowling for heat transfer. Other Cessnas have it behind plexiglas in the left wing which is less optimal.

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